<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <script type="text/javascript" src="../../day03_jQuery/script/jquery-1.7.2.min.js"></script>
    <script type="text/javascript">
        $(function () {
            var arr = ["er", 43, true];
            var $btn = $("button");
            for (var i = 0; i < $btn.length; i++) {
                alert($btn[i]);
            }
        });
    </script>
</head>
<body>
<div id="testDiv">你好</div>
<button id="1">按钮1</button>
<button id="2">按钮2</button>
<button id="3">按钮3</button>
<button id="4">按钮4</button>
</body>
</html>